Process for the hydrocracking of hydrocarbons without a net consumption of hydrogen



United States Patent 3 375,191 PROCESS FOR THE IIYDROCRACKING 0F HY- DROCARBONS WITHOUT A NET CONSUMP- TION OF HYDROGEN William Charles Pfeiferle, Middletown, N.J., assignor to Engelhard Industries, Inc., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 203,487, June 19, 1962. This application Mar. 25, 1966, Ser. No. 537,310

4 Claims. (Cl. 208 112) The present application is a continuation-in-part of my copending application, Ser. No. 203,487, filed June 19, 1962, later abandoned.

This invention relates to the conversion of relatively higher molecular weight hydrocarbons to hydrocarbons of relatively lower molecular weight. More particularly, this invention relates to the conversion of relatively higher molecular weight distillate hydrocarbons to distillate hydrocarbons of relatively lower molecular weight in the presence of hydrogen and a catalyst without a net consumption of hydrogen.

The conversion of higher molecular weight hydrocarbons to lower molecular weight hydrocarbons in the presence of hydrogen and catalyst is a reaction known as hydrocracking. The reaction proceeds with a net consumption of hydrogen, i.e., at least a mole of hydrogen for each cracked hydrocarbon molecule. The reaction has also been proposed for use with higher molecular weight hy' drocarbons such as materials boiling through the kerosene and gas oil ranges to upgrade these stocks to gasoline boiling range materials but the limited availability of low cost hydrogen makes commercial exploitation more costly.

In recent years there has been a considerable investigation of the use of supported platinum or palladium catalysts for hydrocracking. Such hydrooracking catalysts have generally been supported on highly acidicmixed oxide supports, such as silica-alumina, including faujasite sieves, and silica-zirconia. To provide good selectivity for hydrocracking to normally liquid naphtha products, and to minimize gas make and coke production, operation with such highly acidic catalysts has usually been carried out below 800 F. and frequently in the 600 F. to 700 F. temperature range.

I have now discovered a process whereby relatively higher molecular weight hydrocarbons are converted to relatively lower molecular weight hydrocarbons in the presence of hydrogen and a platinum group metal on alumina catalyst and wherein there is no net consumption of hydrogen. The process of this invention essentially involves introducing into a reaction zone containing a platinum metal on alumina catalyst, a C to C alkane, such as methane, ethane or propane, together with the relatively higher molecular weight hydrocarbon and hydrogen. The C to C alkane is generally consumed during the conversion reaction, and there is no net consumption of hydrogen,

The reaction is economically attractive in contradistinction to hydrocracking in that methane is readily availa'ble at low cost and the methane together with any lower alkane by-products can be recycled to extinction permitting yields on both a volume and weight basis with Patented Mar. 26, 1968 respect to 'the relatively higher molecular weight hydrocarbon feed to exceed 100% The process of this invention thus comprises introducing into a reaction zone containing a platinum metal on alumina catalyst having dehydrocyclization activity and reacting a mixture consisting essentially of (A) a relatively higher molecular weight hydrocarbon, (B) a C to 'C alkane and (C) hydrogen in a ratio of at least one 0.05 to 20. Such operation permits cycle lengths of at least '48 hours making less than 0.5% by weight of carbon on feed. Advantageously the ratio of (B) to (A) is greater than 5:1 and can range up to 150:1. Also advantageously the ratio of (C) to (B) is less than 0.3 mole of (C) per mole of (B) and ranges up to 0.7 mole of (C) per mole of (B). The amount of hydrogen present is advantageously only suflicient to prevent C to C alkane decomposition and is in the higher portion of the range during low pressure and/or high temperature operation. Operation at temperatures above about 900 F. should be avoided to prevent thermal cracking, but below the thermal cracking range higher temperatures are to be preferred.

The relatively higher molecular weight hydrocarbon charge stocks which can be converted according to this invention comprise aliphatic hydrocarbons and aromatic hydrocarbons with an aliphatic side chain of at least two carbon atoms. They include, for example, heavy straight run naphtha, kerosene, and gas oil, light and heavy cycle oils from thermal or catalytic cracking, rafiinates obtained by Udex extraction of light and heavy cycle oils,.

and the like, these charge stocks thus have a boiling range from about 400 F. up .to about 750 F.

. The catalysts useful in the process of this invention are those having dehydrocyclization activity and include the platinum group metal on activated alumina catalysts. Preferably the catalysts used in practicing the process of this invention are those which have a' platinum group metal content of 0.1 to 2.5% by weight. The activated alumina must have some acidity which can be enhanced by addition of a small amount of halide, for example, less than 2% halogen. The platinum group metal of the I catalyst is the essential component and these metals include for instance platinum, palladium, rhodium and iridium. A catalyst employed advantageously is a supported platinum catalyst containing for instance about 0.3 to 1.0 percent by weight platinum and the support is alumina characterized for instance by high surface area and large pore size. Such catalysts can be conveniently prepared as described in US. Patents Nos. 2,83 8,444 and 2,838,445.

The process of this invention is illustrated in detail in the following examples:

EXAMPLE 1 A fluoride-free platinum-alumina catalyst produced in a commercial plant which manufactures the catalyst of US. Patent 2,838,444 containing approximately 0.6 I

Weight percent platinum in the form of one-sixteenth inch extrudates in an amount of 20 grams was placed ina one inch inside diameter universal stainless steel reactor tube dispersed with sufficient 8 to 14 mesh tabular alumina to provide a catalyst zone of about 250 cubic centimeters volume. The reactor, after each charging, was placed in. a bronze-block furnace controlled by thermostats. Fed temperatures were measured by means of platinum and! platinum-rhodium thermocouples. Each charge of catallyst was purged with nitrogen gas and then reduced overnight in a slow stream of hydrogen gas at about 900 F. and atmospheric pressure. The mixture of feed and recycle gas passed over the catalyst through the bed andi the eflluent was passed to a small volume high pressure separator from the top of which a gas phase was taken. oif for recycle and from the bottom of which a net product consisting of condensable liquid plus the net gas pro-- duction was withdrawn and introduced into a product stabilizer. In order to minimize both holdup and flowr upsets in the small volume system, the total net product was continuously removed using an air-operated flow control valve actuated by a back pressure recorder-controller. The total net product so removed was fed continuously into a product stabilizer to give a liquid product and a C gas. The gas from the stabilizer was;

metered and then sampled by diverting a portion into am evacuated butyl rubber gas sample bag using a timer actu ated solenoid valve. The recycle gas from the top of thehigh pressure separator was passed into a palladium diffusion unit prior to recycle. The diffusion unit comprised. a jacketed palladium tube of one-eighth inch outside diameter approximately twenty feet long. A pressure gauge indicated the pressure of the through gas after leaving the diifusion unit and a separate pressure gauge indicated the pressure of the substantially pure hydrogen in the jacketed section of the diffusion unit. Substantially pure hydrogen was bled from the jacketed section at controlled rates. The recycle gas then was passed through an Ascarite scrubber and dryer for removal of water and acidic materials such as hydrogen sulfide. The feed system was a conventional pressure drop system including an alumina dryer. The feed was measured volumetrically. The feed and recycle gas dryers reduced the Water content of the total feed to the unit to less than 100 parts of water per million parts by volume of total feed in vapor phase and the Ascarite scrubber substantially completely removed any sulfur from the recycle gas. The unit has proved suitable for accurately determining yield-octane relationships.

The feed charged to the unit was 'a heavy straight man gas oil, about C to C and had the following inspecttions:

ASTM dist, F. (recovery, 96.5% )2 Initial B.P. 401. 427 50% 484 90% 560: RP 574 Sulfur p.p.m 74 Chlorine p.p.m 3.4 Nitrogen --p.p.m 3.4

Analysis of both gas and liquid samples for C through C hydrocarbons was by gas chromatography. Analysis of gas samples for hydrogen was by Orsat. All components of a gas sample were determined independently and then summed as a check against errors. All gas analyses were converted to an air-free basis before use in yield calculations.

The system was pressured with hydrogen and a moleof methane was charged for each mole of liquid hydrocarbon charge stock. After lining out, the unit was operated at a temperature of 800 F., a total pressure of 350 p.s.i.g., a weight hourly space velocity of 2, a gas recycle ratio of 20 to l, and a hydrogen partial pressure in the recycle gas stream during the hours 6 to 24 of 105-107 and during hours 3945 of 55. The run demonstrates a consumption of methane and a net hydrogen production under the run conditions.

The operating conditions, yield and product inspection data are shown in the following Table I. Yields are given as the percent on feed and were calculated on the basis of recovery.

TABLE I Run No. 2,019

Operating Conditions:

Hours on Oil... 6-12 12-18 18-24 39-45 Temp, F..... 800 0 800 800 WHSV 2 2 2 2 Recycle Ratio, Mel/Moi:

Total Gas 20/1 20/1 20/1 20/1 Hydrogen 5. 8 5. 9 5. 8 3.0 Press:

Total p.s.i.g-. 350 350 350 350 Hydrogen (Dlfiusion Unit) p.s.i.a 107 105 55 Yield Based on 100% Recovery:

Hz, Wt. percent 2. 3 2.1 2.1 1. 5 C1, Wt. percent.... 2. 0 -1. 6 2. 2 0. 8 C Wt. percent. 0.7 .6 4 .3 03, Wt. percent. .9 7 6 4 04, Wt. percent. .6 .4 .4 .2 C5, Wt. percent.... 97. 5 97. 8 96. 4 96. 5 (15+, Vol. percent 94. 7 95. 5 96. 1 98. 3 Recovery, Wt. percent 94. 9 99. 7 96. 1 98. 3 Product Inspections:

Aromatics, Vol. percent 51 49 49 44 Vol. percent 05+ to 400 F 15 15 12 9 EXAMPLE 2 In this example, the apparatus and catalyst were the same as employed in Example 1. The feed charged to the unit was a straight run gas oil having the following inspections:

ASTM dist, F.:

The operating conditions, yield and product inspection data are shown in the following Table II. Yields .are given as the percent on feed and were calculated on the basis of 100% recovery. The hydrogen bleed rate represents the hydrogen bled from the jacketed section of the diffusion unit. Again the run demonstrates a net consumptron of methane and a net production of hydrogen under the run conditions.

TABLE II Run No. 2059 Operating Conditions:

- l m H 6 Mm M w%n v m8 35399 5395635 m w a t QO 3M aaam ariaaamm a h A 8LL2 1 r l W 9 6 PM 4 F u% 0 w mfi A .A m -fl m h 0 a 00 311 22405212000 w W 1 6 m %%2 Lw 1 98 m e O 9 e 594. 0 .4. m m t 8 s 8 two ms... asshhsseasoi 0 00 m N F 00 3 0 2 02 001 00m S 8 782Ll 1 H a 0 d 1 S b y 7988 7 45 m d m a h bum wh n sss sfi 990 3 2 24 0 010084 e n O t :1 W4 .9 99 91 W d 9720 7 0 F W 6 n 6 00% W35 AW WA WJ WJAJA 5 .1 n w 3 F QO 3W0 2 .34900100%m 00 u m a m 682L1 1 98 t m w d n n m5 4 65 5572215 nswmm 3 .2001 no 8 e m o N 0. 0 0 n aarszuauaumm 000 30% 00 .989 7 1 t I 58LL2 0 WWZLN 21 999 8 6 U m S O h S. R 00165 012 488688582305 t a t 5 .0 9 549 wfiwuww m5 6733 1 19 14 3 %M U 1% 6 W e OW 3 9 2 1173100007 do ems 0 0 mu m o m n usznm 0 9 t e 8211 a o 5 3 M m ZG mm 62880258233H @1212 003 21 5119305 00 d S H090 3 0 2 9w1-7 420 0 00 .001 524 a m 100 3 7 1 %%3 w .m m m m W 3o cllm 1 GBZLI .1 e .w m m n. e r n am 0mm 1 39 0 80042 056 4134118874 07 m U m T. 1 1 .0 5 7 25.200 100 MLmmm mam L1 &6 M e i d e .m I $6 0 3 0 99 .umaLm w 99 8 m m m t t E h pm w M %0M 9 0 5 34102479231m 00052 0 7 5944114965 30 a S t 1 A LQOQ 3L7 20 2020000 0& 5.097522 ..80 a 0... 99 9 r ou 3 0 11-10000 4 w m W n n T 8 0 4 0 1 .1 t. 8 1 5 0970 01 2 77 554780341 5 5 1 .910 591 432 5 057 65461 17945 75 2 1 .0 3 8 22 278 2 010063 am% mam Laaauaaass m 1% 91 0 .9 4 999 8 0 38201 1 .Mdg "00" u .0%65 eow 7159224767 MW .7. m n m m n m n H L0 Om 3L8 L0 0 0 0 0 03 7 9 e M a u n umao 0 999 flhh I": n C 1 ama wma 9360233481 a d m m m Id m L 9 0 3 9 LLQLQO 4 9 e S e mmLLw a 9 s s e a 0 n .e 0 g a n u "m 0mm wfi 1173334195 m m e m OO m 100. 301 aaordotaaa 9 a n .m mM %2Lw L 999 8 c m n "U v. a r. UIIMIIIUII I d t m 1 W n h .TM 0 .H ...a. ...S8 3 n. R U e n n n d u n a n s a a n "in unmn n. u H w n n E u 1 U m 0 .m o H 5 "nM," mW w S .1 0.. e0 U a on 0 .F I P w m mauneu flm i "w pg 0 a..gB .5 n 0 "m d u u A mn i m F m mno "C .1 O 1 o .8 I U a 5 C0 1 8 t d it n e 0 a H D. ran an? r no m .2 3 a wauan a 9 W0 w 1. E W.1 imm tcw 0 f "11 III mum t m noes... y WW .mRR. ..n. Ole IHTWM P HH 0 u Mm "D IIr.mm a a en. w a ma a ammmmm m m was. m 0 Y Rv mnh Manmm mww wmuuw nflv mWs O nw H D L al g n. wmshmw mmmm tnw m "m x Pw n 0 t d L S v1 G .1 ammammmm m m w m Sh 1 1 y m 0 m t e B 1 4 r t 0 l S U 1 e m v. bma stw ce 1 t HTWM P HmHooownoo mom emb 0 0 n e .1 e r t R Y R P I m m S t t alkane and (C) hydrogen er mole of (A) a hydrogen .s'igg .8768 .8768 .8768 .8857 .8845

I claim:

1. A process for the conversion of relatively higher molecular weight hydrocarbons to hydrocarbons of relatively lower molecular weight without a net consumption of hydrogen which comprises introducing into and maintaining in a reaction zone and reacting a mixture consist- 450 ing essentially of (A) a relatively higher molecular weight hydrocarbon, (B) a C to C in a ratio of at least one mole of (B) -p and a molar ratio of (C) to (B) less than 1:1 at a total pressure of about 50 to about 700 p.s.i.g.,

95 503 partial pressure of less than 200 p.s.i.g., a temperature of about 650 to about 900 F., .a weight hourly space velocity of 0.05 to 20 and in contact with a platinum group metal on acidic alumina catalyst, the reaction period being at least 48 hours in duration and the carbon yield on feed at the end of the reaction period being less than 0.5% by weight.

2. The process of claim 1 wherein the relatively higher molecular weight hydrocarbon has a boiling range of about 400 F. to 750 F., the ratio of (B) to (A) is The operating conditions, yield and product inspection greater than 5:1 and ranges up to 150:1, the ratio of data are shown in the following Table III. Yields are given (C) to (B) is less than. 0.3, and the platinum group metal as the percent on feed and were calculated on the basis on acidic alumina catalyst is platinum on acidic alumina. of 100% recovery. Again the run demonstrates a net 3. A process for the conversion of relatively higher consumption of methane during hours 7 to 58 at a temmolecular weight hydrocarbons to hydrocarbons of rela- Product Inspections (total liquid):

ASTM dist, F. (recovery 98.7%):

Density:

Aromatics, vol. percent Molecular wt. (calculated) Sulfur -p.p.m 79.9 Chlorine p.p.m

perature of about 800 F., a slight net production of 75 tively lower molecular weight without a net consumption of hydrogen and with a net consumption of methane which comprises introducing into and maintaining in a reaction zone and reacting a mixture consisting essentially of (A) a relatively higher molecular weight hydrocarbon, (B) methane and (C) hydrogen in a ratio of at least one mole of (B) per mole of (A) and amolar ratio of (C) to (B) less than 1:1 at a total pressure of about 50 to about 700 p.sti.g., a hydrogen partial pressure of between 20 and 120 p.s.i.g., a temperature of about 650 to about 900 F., a weight hourly space velocity of 0.05 to 20 and in contact with a platinum group metal on acidic alumina catalyst, the reaction period being at least 48 hours in duration and the carbon yield on feed at the end of the reaction period being less than 0.5% by Weight 4. The process of claim 3 wherein the relatively higher molecular weight hydrocarbon has a boiling range of 8 about 400 F. to 750 F., the ratio of (B) to (A) is greater than 5:1 and ranges up to 150:1, the ratio of (C) to (B) is less than 0.3, and the platinum group metal on acidic alumina catalyst is platinum on acidic alumina.

References Cited ABRAHAM RIMENS, Primary Examiner.

DELBERT E. GANTZ, Examiner. 

1. A PROCESS FOR THE CONVERSION OF RELATIVELY HIGHER MOLECULAR WEIGHT HYDROCARBONS TO HYDROCARBONS OF RELATIVELY LOWER MOLECULAR WEIGHT WITHOUT A NET CONSUMPTION OF HYDROGEN WHICH COMPRISES INTRODUCING INTO AND MAINTAINING IN A REACTION ZONE AND REACTING A MIXTURE CONSISTING ESSENTIALLY OF (A) A RELATIVELY HIGHER MOLECULAR WEIGHT HYDROCARBON, (B) A C1 TO C3 ALKANE AND (C) HYDROGEN IN A RATIO OF AT LEAST ONE MOLE OF (B) PER MOLE OF (A) AND A MOLAR RATIO OF (C) TO (B) LESS THAN 1:1 AT A TOTAL PRESSURE OF ABOUT 50 TO ABOUT 700 P.S.I.G., A HYDROGEN PARTIAL PRESSURE OF LESS THAN 200 P.S.I.G., A TEMPERATURE OF ABOUT 650* TO ABOUT 900*F., A WEIGHT HOURLY SPACE VELOCITY OF 0.05 TO 20 AND IN CONTACT WITH A PLATINUM GROUP METAL ON ACIDIC ALUMINA CATALYST, THE REACTION PERIOD BEING AT LEAST 48 HOURS IN DURATION AND THE CARBON YIELD ON FEED AT THE END OF THE REACTION PERIOD BEING LESS THAN 0.5% BY WEIGHT. 